bmxguitarsbmx wrote:JOK3RX,Do you have the part numbers for your diptrace schematic?

I could syncronize my part numbers with yours, and that may help us check for errors.

Thanks for your work

No, unfortunately the guy that sent me the schematic only used the part values.. If you use my numbering schema it will be all jacked up. I just updated the pics just now so you might want to download them again... I had some issues with the vref that I think I corrected.

psychodave wrote:I own this pedal and really like it, but I wish it had a mid pot. Can anyone point me in the right direction to where I can add mids ?

Well hello there psychodave!

Sure... Just open yours up, get some more good pics of the guts and upload them so we can finish tracing this damn thing It would also be helpful if you could verify traces/connections with a meter if needed but, I would settle for just some more good gut shots... After that we can have a crack at that mid control you want. Do we have a deal?

I breadboarded bmxguitarsbmx's schematic to see how it came up. All the controls functioned more or less as expected apart from the bass control which did nothing audible. Replacing the pair of 33k resistors in his schematic with the unit's 3k3 values yielded a pretty useful control. The overall tone is pretty middley but that's kinda the Marshall thing. It's a good starting point for experimentation I reckon. Great work from the guys at FSB once again!

psychodave wrote:The 3 op amps are all TL072. The mustard colored cap is 120. The standing blue and 2 black caps from top left clockwise are 22uf, 47uf and 22uf.

Looks like a design flaw with the volume pot. A trace is cut the side without the pots facing you. Center or right lugs. Notice the added side on the volume on the pot side.

Yeah, Groovenut already said it.. The piece of bus wire on volume pot from lug 1 to the casing is to ground the enclosure.

Not sure about the cut trace you are referring to? This kinda looks like an xacto blade scrape.

If they cut the ground trace on the board connecting to lug 1 on the volume pot then I am not sure why they went and soldered the bus wire from lug 1 to the pot casing?

The pictures helped verify some stuff from the frist batch of pictures that were posted but still need some verification on some stuff. Would be nice if somebody who owns the pedal could tie all of the ground points together... shouldn't be hard, just put one probe from your meter on a known ground like the ground on the power connector and leave it there.. then use the other probe to hit all of the points on the board, use the audible continuity check and the ones that make a beep sound are ground... If you do be sure to get the via's as well

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wake01 wrote:I breadboarded bmxguitarsbmx's schematic to see how it came up. All the controls functioned more or less as expected apart from the bass control which did nothing audible. Replacing the pair of 33k resistors in his schematic with the unit's 3k3 values yielded a pretty useful control. The overall tone is pretty middley but that's kinda the Marshall thing. It's a good starting point for experimentation I reckon. Great work from the guys at FSB once again!

Thanks for your efforts wake01. Very interesting. I calculated a midrange boost at 3.3k... That's why I swapped the values. Does it work on the bass region at 3.3k though?

Glad I don't have to apologize too hard for leading you astray. The presence control is definitely wrong, I'm pretty lost to what it actually is.

the 22k resistor before the last clipping might want to be smaller, if you feel like trying a 2.2k.

I did a lot of work on this the last couple of days and have some corrections for bmxguitarsbmx's schematic (can't face drawing it from scratch with my lame skills lol). I'll attach the modified version if you care to make the corrections and post it.

I went over the pics and found a few things. One helpful strategy was that I relabelled all the parts according to the board because layout guys usually number them in order which helps to work out just where some parts might fit in. It helped a lot. I'm not saying it's correct but it does work pretty well now, including the Presence pot. One thing that may not be right is tagging the final pair of LED clippers underneath C14, it works both ways but sounds a bit better imo this way.

cheers

Richie

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Sync'd my scheme with Richie's part numbers. Much appreciated and cool to hear you have proto'd it. From here it might be useful to just get a list of part numbers and values that are missing. Just to get an idea of how far off we are. Quite a few Power supply caps, and likely some caps to drop the dc gain of a few of those stages.

3.3k for the "bass" control still seems a little more like a mid boost. 22k each sims out to around 100Hz. Can't for the life of me find these parts on the board though. Part numbers above 900 are ?'s. Clipping after IC2B is probably the most interesting thing.

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bmxguitarsbmx wrote:Sync'd my scheme with Richie's part numbers. Much appreciated and cool to hear you have proto'd it. From here it might be useful to just get a list of part numbers and values that are missing. Just to get an idea of how far off we are. Quite a few Power supply caps, and likely some caps to drop the dc gain of a few of those stages.

3.3k for the "bass" control still seems a little more like a mid boost. 22k each sims out to around 100Hz. Can't for the life of me find these parts on the board though. Part numbers above 900 are ?'s. Clipping after IC2B is probably the most interesting thing.

Thanks for the redraw. When I did the part number listing thing there were a few part numbers I couldn't find on the pics of the board. Don't know if they were left out but it seemed unlikely. The ones I couldn't find were R6, R16, R17, C5, C6, C7 and C10. R16-R17 would fall around the gain trim/presence pot area...

Also the bass control is odd, it changes from an essentially flat response to a mid peak as the schematic would suggest and you're right the mid peak is kinda high. Couldn't see the relevant resistors in the twin-T network though so it's just based on the previous schematic. With 33k there it didn't do much audibly. Might try some other values.

bmxguitarsbmx wrote:Sync'd my scheme with Richie's part numbers. Much appreciated and cool to hear you have proto'd it. From here it might be useful to just get a list of part numbers and values that are missing. Just to get an idea of how far off we are. Quite a few Power supply caps, and likely some caps to drop the dc gain of a few of those stages.

A couple of minor corrections, your C5 should be C9 and there isn't a 120pF (your C10) around IC2B, I looked hard on the board and didn't use one in the proto.

First off, I'm new here and just want to thank everyone for all the great work done here!Just saw this and have been wanting to build this for a while. Thanks for posting! The final picture there seems to be cut off on the right hand side. Is there a way to repost it?

Woops, sorry about that. The picture is actually cut. It is a 10k resistor to the volume pot. Same as the schem on page 3. Wish I was good at using a schem drawing program for clarity sake. Hoping someone will take my work to the next level by drawing up a proper schem. Also, the original owner will be snagging it by the weekend, so if anyone has anything they think I should double check, please ask!